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			<h1>Java 运算符</h1>

<p>计算机的最基本用途之一就是执行数学运算，作为一门计算机语言，Java也提供了一套丰富的运算符来操纵变量。我们可以把运算符分成以下几组：</p>
<ul>
	<li>
		算术运算符</li>
	<li>
		关系运算符</li>
	<li>
		位运算符</li>
	<li>
		逻辑运算符</li>
	<li>
		赋值运算符</li>
	<li>
		其他运算符</li>
</ul>
<h2>算术运算符</h2>
<p>算术运算符用在数学表达式中，它们的作用和在数学中的作用一样。下表列出了所有的算术运算符。</p>
<p>表格中的实例假设整数变量A的值为10，变量B的值为20：</p>
<table class="reference">
	<tbody>
		<tr>
			<th style="width:64px;">
			操作符</th>
			<th style="width:273px;">
			描述</th>
			<th style="width:111px;">
			例子</th>
		</tr>
		<tr>
			<td style="width:64px;">
				+</td>
			<td style="width:273px;">
				加法 - 相加运算符两侧的值</td>
			<td style="width:111px;">
				A + B 等于 30</td>
		</tr>
		<tr>
			<td style="width:64px;">
				-</td>
			<td style="width:273px;">
				减法 - 左操作数减去右操作数</td>
			<td style="width:111px;">
				A – B 等于 -10</td>
		</tr>
		<tr>
			<td style="width:64px;">
				*</td>
			<td style="width:273px;">
				乘法 - 相乘操作符两侧的值</td>
			<td style="width:111px;">
				A * B等于200</td>
		</tr>
		<tr>
			<td style="width:64px;">
				/</td>
			<td style="width:273px;">
				除法 - 左操作数除以右操作数</td>
			<td style="width:111px;">
				B / A等于2</td>
		</tr>
		<tr>
			<td style="width:64px;">
				％</td>
			<td style="width:273px;">
				取余 - 左操作数除以右操作数的余数</td>
			<td style="width:111px;">
				B%A等于0</td>
		</tr>
		<tr>
			<td style="width:64px;">
				++</td>
			<td style="width:273px;">
				自增: 操作数的值增加1</td>
			<td style="width:111px;">
				B++ 或 ++B 等于 21（区别详见下文）</td>
		</tr>
		<tr>
			<td style="width:64px;">
				--</td>
			<td style="width:273px;">
				自减: 操作数的值减少1</td>
			<td style="width:111px;">
				B-- 或 --B 等于 19（区别详见下文）</td>
		</tr>
	</tbody>
</table>
<h3>实例</h3>
<p>下面的简单示例程序演示了算术运算符。复制并粘贴下面的 Java 程序并保存为 Test.java 文件，然后编译并运行这个程序：</p>
<div class="example"> 
<h2 class="example">实例</h2> 
<div class="example_code">
<div class="hl-main"><span class="hl-reserved">public</span><span class="hl-code"> </span><span class="hl-reserved">class</span><span class="hl-code"> </span><span class="hl-identifier">Test</span><span class="hl-code"> </span><span class="hl-brackets">{</span><span class="hl-code">
 
  </span><span class="hl-reserved">public</span><span class="hl-code"> </span><span class="hl-types">static</span><span class="hl-code"> </span><span class="hl-types">void</span><span class="hl-code"> </span><span class="hl-identifier">main</span><span class="hl-brackets">(</span><span class="hl-identifier">String</span><span class="hl-brackets">[</span><span class="hl-brackets">]</span><span class="hl-code"> </span><span class="hl-identifier">args</span><span class="hl-brackets">)</span><span class="hl-code"> </span><span class="hl-brackets">{</span><span class="hl-code">
     </span><span class="hl-types">int</span><span class="hl-code"> </span><span class="hl-identifier">a</span><span class="hl-code"> = </span><span class="hl-number">10</span><span class="hl-code">;
     </span><span class="hl-types">int</span><span class="hl-code"> </span><span class="hl-identifier">b</span><span class="hl-code"> = </span><span class="hl-number">20</span><span class="hl-code">;
     </span><span class="hl-types">int</span><span class="hl-code"> </span><span class="hl-identifier">c</span><span class="hl-code"> = </span><span class="hl-number">25</span><span class="hl-code">;
     </span><span class="hl-types">int</span><span class="hl-code"> </span><span class="hl-identifier">d</span><span class="hl-code"> = </span><span class="hl-number">25</span><span class="hl-code">;
     </span><span class="hl-identifier">System</span><span class="hl-code">.</span><span class="hl-identifier">out</span><span class="hl-code">.</span><span class="hl-identifier">println</span><span class="hl-brackets">(</span><span class="hl-quotes">&quot;</span><span class="hl-string">a + b = </span><span class="hl-quotes">&quot;</span><span class="hl-code"> + </span><span class="hl-brackets">(</span><span class="hl-identifier">a</span><span class="hl-code"> + </span><span class="hl-identifier">b</span><span class="hl-brackets">)</span><span class="hl-code"> </span><span class="hl-brackets">)</span><span class="hl-code">;
     </span><span class="hl-identifier">System</span><span class="hl-code">.</span><span class="hl-identifier">out</span><span class="hl-code">.</span><span class="hl-identifier">println</span><span class="hl-brackets">(</span><span class="hl-quotes">&quot;</span><span class="hl-string">a - b = </span><span class="hl-quotes">&quot;</span><span class="hl-code"> + </span><span class="hl-brackets">(</span><span class="hl-identifier">a</span><span class="hl-code"> - </span><span class="hl-identifier">b</span><span class="hl-brackets">)</span><span class="hl-code"> </span><span class="hl-brackets">)</span><span class="hl-code">;
     </span><span class="hl-identifier">System</span><span class="hl-code">.</span><span class="hl-identifier">out</span><span class="hl-code">.</span><span class="hl-identifier">println</span><span class="hl-brackets">(</span><span class="hl-quotes">&quot;</span><span class="hl-string">a * b = </span><span class="hl-quotes">&quot;</span><span class="hl-code"> + </span><span class="hl-brackets">(</span><span class="hl-identifier">a</span><span class="hl-code"> * </span><span class="hl-identifier">b</span><span class="hl-brackets">)</span><span class="hl-code"> </span><span class="hl-brackets">)</span><span class="hl-code">;
     </span><span class="hl-identifier">System</span><span class="hl-code">.</span><span class="hl-identifier">out</span><span class="hl-code">.</span><span class="hl-identifier">println</span><span class="hl-brackets">(</span><span class="hl-quotes">&quot;</span><span class="hl-string">b / a = </span><span class="hl-quotes">&quot;</span><span class="hl-code"> + </span><span class="hl-brackets">(</span><span class="hl-identifier">b</span><span class="hl-code"> / </span><span class="hl-identifier">a</span><span class="hl-brackets">)</span><span class="hl-code"> </span><span class="hl-brackets">)</span><span class="hl-code">;
     </span><span class="hl-identifier">System</span><span class="hl-code">.</span><span class="hl-identifier">out</span><span class="hl-code">.</span><span class="hl-identifier">println</span><span class="hl-brackets">(</span><span class="hl-quotes">&quot;</span><span class="hl-string">b % a = </span><span class="hl-quotes">&quot;</span><span class="hl-code"> + </span><span class="hl-brackets">(</span><span class="hl-identifier">b</span><span class="hl-code"> % </span><span class="hl-identifier">a</span><span class="hl-brackets">)</span><span class="hl-code"> </span><span class="hl-brackets">)</span><span class="hl-code">;
     </span><span class="hl-identifier">System</span><span class="hl-code">.</span><span class="hl-identifier">out</span><span class="hl-code">.</span><span class="hl-identifier">println</span><span class="hl-brackets">(</span><span class="hl-quotes">&quot;</span><span class="hl-string">c % a = </span><span class="hl-quotes">&quot;</span><span class="hl-code"> + </span><span class="hl-brackets">(</span><span class="hl-identifier">c</span><span class="hl-code"> % </span><span class="hl-identifier">a</span><span class="hl-brackets">)</span><span class="hl-code"> </span><span class="hl-brackets">)</span><span class="hl-code">;
     </span><span class="hl-identifier">System</span><span class="hl-code">.</span><span class="hl-identifier">out</span><span class="hl-code">.</span><span class="hl-identifier">println</span><span class="hl-brackets">(</span><span class="hl-quotes">&quot;</span><span class="hl-string">a++   = </span><span class="hl-quotes">&quot;</span><span class="hl-code"> +  </span><span class="hl-brackets">(</span><span class="hl-identifier">a</span><span class="hl-code">++</span><span class="hl-brackets">)</span><span class="hl-code"> </span><span class="hl-brackets">)</span><span class="hl-code">;
     </span><span class="hl-identifier">System</span><span class="hl-code">.</span><span class="hl-identifier">out</span><span class="hl-code">.</span><span class="hl-identifier">println</span><span class="hl-brackets">(</span><span class="hl-quotes">&quot;</span><span class="hl-string">a--   = </span><span class="hl-quotes">&quot;</span><span class="hl-code"> +  </span><span class="hl-brackets">(</span><span class="hl-identifier">a</span><span class="hl-code">--</span><span class="hl-brackets">)</span><span class="hl-code"> </span><span class="hl-brackets">)</span><span class="hl-code">;
     </span><span class="hl-comment">//</span><span class="hl-comment"> 查看  d++ 与 ++d 的不同</span><span class="hl-comment"></span><span class="hl-code">
     </span><span class="hl-identifier">System</span><span class="hl-code">.</span><span class="hl-identifier">out</span><span class="hl-code">.</span><span class="hl-identifier">println</span><span class="hl-brackets">(</span><span class="hl-quotes">&quot;</span><span class="hl-string">d++   = </span><span class="hl-quotes">&quot;</span><span class="hl-code"> +  </span><span class="hl-brackets">(</span><span class="hl-identifier">d</span><span class="hl-code">++</span><span class="hl-brackets">)</span><span class="hl-code"> </span><span class="hl-brackets">)</span><span class="hl-code">;
     </span><span class="hl-identifier">System</span><span class="hl-code">.</span><span class="hl-identifier">out</span><span class="hl-code">.</span><span class="hl-identifier">println</span><span class="hl-brackets">(</span><span class="hl-quotes">&quot;</span><span class="hl-string">++d   = </span><span class="hl-quotes">&quot;</span><span class="hl-code"> +  </span><span class="hl-brackets">(</span><span class="hl-code">++</span><span class="hl-identifier">d</span><span class="hl-brackets">)</span><span class="hl-code"> </span><span class="hl-brackets">)</span><span class="hl-code">;
  </span><span class="hl-brackets">}</span><span class="hl-code">
</span><span class="hl-brackets">}</span></div>
</div><br>
<a target="_blank" href="../try/showjava.php?filename=test_operator" class="showbtn" rel="noopener noreferrer">运行实例 »</a>
</div>
<p>以上实例编译运行结果如下：</p>
<pre>
a + b = 30
a - b = -10
a * b = 200
b / a = 2
b % a = 0
c % a = 5
a++   = 10
a--   = 11
d++   = 25
++d   = 27
</pre>
<h3>自增自减运算符</h3>
<p><strong>1、自增（++）自减（--）运算符</strong>是一种特殊的算术运算符，在算术运算符中需要两个操作数来进行运算，而自增自减运算符是一个操作数。</p>
<div class="example"> 
<h2 class="example">实例</h2> 
<div class="example_code">
<div class="hl-main"><span class="hl-reserved">public</span><span class="hl-code"> </span><span class="hl-reserved">class</span><span class="hl-code"> </span><span class="hl-identifier">selfAddMinus</span><span class="hl-brackets">{</span><span class="hl-code">
    </span><span class="hl-reserved">public</span><span class="hl-code"> </span><span class="hl-types">static</span><span class="hl-code"> </span><span class="hl-types">void</span><span class="hl-code"> </span><span class="hl-identifier">main</span><span class="hl-brackets">(</span><span class="hl-identifier">String</span><span class="hl-brackets">[</span><span class="hl-brackets">]</span><span class="hl-code"> </span><span class="hl-identifier">args</span><span class="hl-brackets">)</span><span class="hl-brackets">{</span><span class="hl-code">
        </span><span class="hl-types">int</span><span class="hl-code"> </span><span class="hl-identifier">a</span><span class="hl-code"> = </span><span class="hl-number">3</span><span class="hl-code">;</span><span class="hl-comment">//</span><span class="hl-comment">定义一个变量；</span><span class="hl-comment"></span><span class="hl-code">
        </span><span class="hl-types">int</span><span class="hl-code"> </span><span class="hl-identifier">b</span><span class="hl-code"> = ++</span><span class="hl-identifier">a</span><span class="hl-code">;</span><span class="hl-comment">//</span><span class="hl-comment">自增运算</span><span class="hl-comment"></span><span class="hl-code">
        </span><span class="hl-types">int</span><span class="hl-code"> </span><span class="hl-identifier">c</span><span class="hl-code"> = </span><span class="hl-number">3</span><span class="hl-code">;
        </span><span class="hl-types">int</span><span class="hl-code"> </span><span class="hl-identifier">d</span><span class="hl-code"> = --</span><span class="hl-identifier">c</span><span class="hl-code">;</span><span class="hl-comment">//</span><span class="hl-comment">自减运算</span><span class="hl-comment"></span><span class="hl-code">
        </span><span class="hl-identifier">System</span><span class="hl-code">.</span><span class="hl-identifier">out</span><span class="hl-code">.</span><span class="hl-identifier">println</span><span class="hl-brackets">(</span><span class="hl-quotes">&quot;</span><span class="hl-string">进行自增运算后的值等于</span><span class="hl-quotes">&quot;</span><span class="hl-code">+</span><span class="hl-identifier">b</span><span class="hl-brackets">)</span><span class="hl-code">;
        </span><span class="hl-identifier">System</span><span class="hl-code">.</span><span class="hl-identifier">out</span><span class="hl-code">.</span><span class="hl-identifier">println</span><span class="hl-brackets">(</span><span class="hl-quotes">&quot;</span><span class="hl-string">进行自减运算后的值等于</span><span class="hl-quotes">&quot;</span><span class="hl-code">+</span><span class="hl-identifier">d</span><span class="hl-brackets">)</span><span class="hl-code">;
    </span><span class="hl-brackets">}</span><span class="hl-code">
</span><span class="hl-brackets">}</span></div>
</div>
</div>
<p>运行结果为：</p>
<pre>
进行自增运算后的值等于4
进行自减运算后的值等于2</pre>
<p>解析：</p>
<ul>
<li><p>int b = ++a; 拆分运算过程为: a=a+1=4; b=a=4, 最后结果为b=4,a=4</p>
</li><li><p>
int d = --c; 拆分运算过程为: c=c-1=2; d=c=2, 最后结果为d=2,c=2</p></li>
</ul>
<p><strong>2、前缀自增自减法(++a,--a): </strong>先进行自增或者自减运算，再进行表达式运算。</p></p>
<p><strong>3、后缀自增自减法(a++,a--): </strong>先进行表达式运算，再进行自增或者自减运算
实例：</p>
<div class="example"> 
<h2 class="example">实例</h2> 
<div class="example_code">
<div class="hl-main"><span class="hl-reserved">public</span><span class="hl-code"> </span><span class="hl-reserved">class</span><span class="hl-code"> </span><span class="hl-identifier">selfAddMinus</span><span class="hl-brackets">{</span><span class="hl-code">
    </span><span class="hl-reserved">public</span><span class="hl-code"> </span><span class="hl-types">static</span><span class="hl-code"> </span><span class="hl-types">void</span><span class="hl-code"> </span><span class="hl-identifier">main</span><span class="hl-brackets">(</span><span class="hl-identifier">String</span><span class="hl-brackets">[</span><span class="hl-brackets">]</span><span class="hl-code"> </span><span class="hl-identifier">args</span><span class="hl-brackets">)</span><span class="hl-brackets">{</span><span class="hl-code">
        </span><span class="hl-types">int</span><span class="hl-code"> </span><span class="hl-identifier">a</span><span class="hl-code"> = </span><span class="hl-number">5</span><span class="hl-code">;</span><span class="hl-comment">//</span><span class="hl-comment">定义一个变量；</span><span class="hl-comment"></span><span class="hl-code">
        </span><span class="hl-types">int</span><span class="hl-code"> </span><span class="hl-identifier">b</span><span class="hl-code"> = </span><span class="hl-number">5</span><span class="hl-code">;
        </span><span class="hl-types">int</span><span class="hl-code"> </span><span class="hl-identifier">x</span><span class="hl-code"> = </span><span class="hl-number">2</span><span class="hl-code">*++</span><span class="hl-identifier">a</span><span class="hl-code">;
        </span><span class="hl-types">int</span><span class="hl-code"> </span><span class="hl-identifier">y</span><span class="hl-code"> = </span><span class="hl-number">2</span><span class="hl-code">*</span><span class="hl-identifier">b</span><span class="hl-code">++;
        </span><span class="hl-identifier">System</span><span class="hl-code">.</span><span class="hl-identifier">out</span><span class="hl-code">.</span><span class="hl-identifier">println</span><span class="hl-brackets">(</span><span class="hl-quotes">&quot;</span><span class="hl-string">自增运算符前缀运算后a=</span><span class="hl-quotes">&quot;</span><span class="hl-code">+</span><span class="hl-identifier">a</span><span class="hl-code">+</span><span class="hl-quotes">&quot;</span><span class="hl-string">,x=</span><span class="hl-quotes">&quot;</span><span class="hl-code">+</span><span class="hl-identifier">x</span><span class="hl-brackets">)</span><span class="hl-code">;
        </span><span class="hl-identifier">System</span><span class="hl-code">.</span><span class="hl-identifier">out</span><span class="hl-code">.</span><span class="hl-identifier">println</span><span class="hl-brackets">(</span><span class="hl-quotes">&quot;</span><span class="hl-string">自增运算符后缀运算后b=</span><span class="hl-quotes">&quot;</span><span class="hl-code">+</span><span class="hl-identifier">b</span><span class="hl-code">+</span><span class="hl-quotes">&quot;</span><span class="hl-string">,y=</span><span class="hl-quotes">&quot;</span><span class="hl-code">+</span><span class="hl-identifier">y</span><span class="hl-brackets">)</span><span class="hl-code">;
    </span><span class="hl-brackets">}</span><span class="hl-code">
</span><span class="hl-brackets">}</span></div>
</div>
</div>
<p>运行结果为：</p>
<pre>
自增运算符前缀运算后a=6，x=12
自增运算符后缀运算后b=6，y=10</pre>
<hr>
<h2>关系运算符</h2>

<p>下表为Java支持的关系运算符</p>
<p>表格中的实例整数变量A的值为10，变量B的值为20：</p>

<table class="reference">
	<tbody>
		<tr>
			<th style="width:42px;">
				运算符</th>
			<th style="width:407px;">
				描述</th>
			<th style="width:128px;">
				例子</th>
		</tr>
		<tr>
			<td style="width:42px;">
				==</td>
			<td style="width:407px;">
				检查如果两个操作数的值是否相等，如果相等则条件为真。</td>
			<td style="width:128px;">
				（A == B）为假。</td>
		</tr>
		<tr>
			<td style="width:42px;">
				!=</td>
			<td style="width:407px;">
				检查如果两个操作数的值是否相等，如果值不相等则条件为真。</td>
			<td style="width:128px;">
				(A != B) 为真。</td>
		</tr>
		<tr>
			<td style="width:42px;">
				&gt;&nbsp;</td>
			<td style="width:407px;">
				检查左操作数的值是否大于右操作数的值，如果是那么条件为真。</td>
			<td style="width:128px;">
				（A&gt; B）为假。</td>
		</tr>
		<tr>
			<td style="width:42px;">
				&lt;&nbsp;</td>
			<td style="width:407px;">
				检查左操作数的值是否小于右操作数的值，如果是那么条件为真。</td>
			<td style="width:128px;">
				（A &lt;B）为真。</td>
		</tr>
		<tr>
			<td style="width:42px;">
				&gt;=</td>
			<td style="width:407px;">
				检查左操作数的值是否大于或等于右操作数的值，如果是那么条件为真。</td>
			<td style="width:128px;">
				（A&gt; = B）为假。</td>
		</tr>
		<tr>
			<td style="width:42px;">
				&lt;=</td>
			<td style="width:407px;">
				检查左操作数的值是否小于或等于右操作数的值，如果是那么条件为真。</td>
			<td style="width:128px;">
				（A &lt;= B）为真。</td>
		</tr>
	</tbody>
</table>

<h3>实例</h3>
<p>下面的简单示例程序演示了关系运算符。复制并粘贴下面的Java程序并保存为Test.java文件，然后编译并运行这个程序：</p>
<div class="example">
<h2 class="example">Test.java 文件代码：</h2> 
<div class="example_code">
<div class="hl-main"><span class="hl-reserved">public</span><span class="hl-code"> </span><span class="hl-reserved">class</span><span class="hl-code"> </span><span class="hl-identifier">Test</span><span class="hl-code"> </span><span class="hl-brackets">{</span><span class="hl-code">
 
  </span><span class="hl-reserved">public</span><span class="hl-code"> </span><span class="hl-types">static</span><span class="hl-code"> </span><span class="hl-types">void</span><span class="hl-code"> </span><span class="hl-identifier">main</span><span class="hl-brackets">(</span><span class="hl-identifier">String</span><span class="hl-brackets">[</span><span class="hl-brackets">]</span><span class="hl-code"> </span><span class="hl-identifier">args</span><span class="hl-brackets">)</span><span class="hl-code"> </span><span class="hl-brackets">{</span><span class="hl-code">
     </span><span class="hl-types">int</span><span class="hl-code"> </span><span class="hl-identifier">a</span><span class="hl-code"> = </span><span class="hl-number">10</span><span class="hl-code">;
     </span><span class="hl-types">int</span><span class="hl-code"> </span><span class="hl-identifier">b</span><span class="hl-code"> = </span><span class="hl-number">20</span><span class="hl-code">;
     </span><span class="hl-identifier">System</span><span class="hl-code">.</span><span class="hl-identifier">out</span><span class="hl-code">.</span><span class="hl-identifier">println</span><span class="hl-brackets">(</span><span class="hl-quotes">&quot;</span><span class="hl-string">a == b = </span><span class="hl-quotes">&quot;</span><span class="hl-code"> + </span><span class="hl-brackets">(</span><span class="hl-identifier">a</span><span class="hl-code"> == </span><span class="hl-identifier">b</span><span class="hl-brackets">)</span><span class="hl-code"> </span><span class="hl-brackets">)</span><span class="hl-code">;
     </span><span class="hl-identifier">System</span><span class="hl-code">.</span><span class="hl-identifier">out</span><span class="hl-code">.</span><span class="hl-identifier">println</span><span class="hl-brackets">(</span><span class="hl-quotes">&quot;</span><span class="hl-string">a != b = </span><span class="hl-quotes">&quot;</span><span class="hl-code"> + </span><span class="hl-brackets">(</span><span class="hl-identifier">a</span><span class="hl-code"> != </span><span class="hl-identifier">b</span><span class="hl-brackets">)</span><span class="hl-code"> </span><span class="hl-brackets">)</span><span class="hl-code">;
     </span><span class="hl-identifier">System</span><span class="hl-code">.</span><span class="hl-identifier">out</span><span class="hl-code">.</span><span class="hl-identifier">println</span><span class="hl-brackets">(</span><span class="hl-quotes">&quot;</span><span class="hl-string">a &gt; b = </span><span class="hl-quotes">&quot;</span><span class="hl-code"> + </span><span class="hl-brackets">(</span><span class="hl-identifier">a</span><span class="hl-code"> &gt; </span><span class="hl-identifier">b</span><span class="hl-brackets">)</span><span class="hl-code"> </span><span class="hl-brackets">)</span><span class="hl-code">;
     </span><span class="hl-identifier">System</span><span class="hl-code">.</span><span class="hl-identifier">out</span><span class="hl-code">.</span><span class="hl-identifier">println</span><span class="hl-brackets">(</span><span class="hl-quotes">&quot;</span><span class="hl-string">a &lt; b = </span><span class="hl-quotes">&quot;</span><span class="hl-code"> + </span><span class="hl-brackets">(</span><span class="hl-identifier">a</span><span class="hl-code"> &lt; </span><span class="hl-identifier">b</span><span class="hl-brackets">)</span><span class="hl-code"> </span><span class="hl-brackets">)</span><span class="hl-code">;
     </span><span class="hl-identifier">System</span><span class="hl-code">.</span><span class="hl-identifier">out</span><span class="hl-code">.</span><span class="hl-identifier">println</span><span class="hl-brackets">(</span><span class="hl-quotes">&quot;</span><span class="hl-string">b &gt;= a = </span><span class="hl-quotes">&quot;</span><span class="hl-code"> + </span><span class="hl-brackets">(</span><span class="hl-identifier">b</span><span class="hl-code"> &gt;= </span><span class="hl-identifier">a</span><span class="hl-brackets">)</span><span class="hl-code"> </span><span class="hl-brackets">)</span><span class="hl-code">;
     </span><span class="hl-identifier">System</span><span class="hl-code">.</span><span class="hl-identifier">out</span><span class="hl-code">.</span><span class="hl-identifier">println</span><span class="hl-brackets">(</span><span class="hl-quotes">&quot;</span><span class="hl-string">b &lt;= a = </span><span class="hl-quotes">&quot;</span><span class="hl-code"> + </span><span class="hl-brackets">(</span><span class="hl-identifier">b</span><span class="hl-code"> &lt;= </span><span class="hl-identifier">a</span><span class="hl-brackets">)</span><span class="hl-code"> </span><span class="hl-brackets">)</span><span class="hl-code">;
  </span><span class="hl-brackets">}</span><span class="hl-code">
</span><span class="hl-brackets">}</span></div>
</div>
</div>

<p>以上实例编译运行结果如下：</p>
<pre>
a == b = false
a != b = true
a &gt; b = false
a &lt; b = true
b &gt;= a = true
b &lt;= a = false
</pre>
<hr><h2>
位运算符</h2>
<p>

Java定义了位运算符，应用于整数类型(int)，长整型(long)，短整型(short)，字符型(char)，和字节型(byte)等类型。
</p>
<p>
位运算符作用在所有的位上，并且按位运算。假设a = 60，b = 13;它们的二进制格式表示将如下：</p>
<pre>
A = 0011 1100
B = 0000 1101
-----------------
A&amp;B = 0000 1100
A | B = 0011 1101
A ^ B = 0011 0001
~A= 1100 0011
</pre>
<p>下表列出了位运算符的基本运算，假设整数变量 A 的值为 60 和变量 B 的值为 13：</p>
<table class="reference">
	<tbody>
		<tr>
			<th style="width:57px;">
				操作符</th>
			<th style="width:372px;">
				描述</th>
			<th style="width:148px;">
				例子</th>
		</tr>
		<tr>
			<td style="width:57px;">
				＆</td>
			<td style="width:372px;">
				如果相对应位都是1，则结果为1，否则为0</td>
			<td style="width:148px;">
				（A＆B），得到12，即0000 1100</td>
		</tr>
		<tr>
			<td style="width:57px;">
				|</td>
			<td style="width:372px;">
				如果相对应位都是 0，则结果为 0，否则为 1</td>
			<td style="width:148px;">
				（A | B）得到61，即 0011 1101</td>
		</tr>
		<tr>
			<td style="width:57px;">
				^</td>
			<td style="width:372px;">
				如果相对应位值相同，则结果为0，否则为1</td>
			<td style="width:148px;">
				（A ^ B）得到49，即 0011 0001</td>
		</tr>
		<tr>
			<td style="width:57px;">
				〜</td>
			<td style="width:372px;">
				按位取反运算符翻转操作数的每一位，即0变成1，1变成0。</td>
			<td style="width:148px;">
				（〜A）得到-61，即1100 0011</td>
		</tr>
		<tr>
			<td style="width:57px;">
				&lt;&lt;&nbsp;</td>
			<td style="width:372px;">
				按位左移运算符。左操作数按位左移右操作数指定的位数。</td>
			<td style="width:148px;">
				A &lt;&lt; 2得到240，即 1111 0000</td>
		</tr>
		<tr>
			<td style="width:57px;">
				&gt;&gt;&nbsp;</td>
			<td style="width:372px;">
				按位右移运算符。左操作数按位右移右操作数指定的位数。</td>
			<td style="width:148px;">
				A &gt;&gt; 2得到15即 1111</td>
		</tr>
		<tr>
			<td style="width:57px;">
				&gt;&gt;&gt;&nbsp;</td>
			<td style="width:372px;">
				按位右移补零操作符。左操作数的值按右操作数指定的位数右移，移动得到的空位以零填充。</td>
			<td style="width:148px;">
				A&gt;&gt;&gt;2得到15即0000 1111</td>
		</tr>
	</tbody>
</table>
<h3>实例</h3>
<p>下面的简单示例程序演示了位运算符。复制并粘贴下面的Java程序并保存为Test.java文件，然后编译并运行这个程序：
</p>
<div class="example">
<h2 class="example">Test.java 文件代码：</h2> 
<div class="example_code">
<div class="hl-main"><span class="hl-reserved">public</span><span class="hl-code"> </span><span class="hl-reserved">class</span><span class="hl-code"> </span><span class="hl-identifier">Test</span><span class="hl-code"> </span><span class="hl-brackets">{</span><span class="hl-code">
  </span><span class="hl-reserved">public</span><span class="hl-code"> </span><span class="hl-types">static</span><span class="hl-code"> </span><span class="hl-types">void</span><span class="hl-code"> </span><span class="hl-identifier">main</span><span class="hl-brackets">(</span><span class="hl-identifier">String</span><span class="hl-brackets">[</span><span class="hl-brackets">]</span><span class="hl-code"> </span><span class="hl-identifier">args</span><span class="hl-brackets">)</span><span class="hl-code"> </span><span class="hl-brackets">{</span><span class="hl-code">
     </span><span class="hl-types">int</span><span class="hl-code"> </span><span class="hl-identifier">a</span><span class="hl-code"> = </span><span class="hl-number">60</span><span class="hl-code">; </span><span class="hl-comment">/*</span><span class="hl-comment"> 60 = 0011 1100 </span><span class="hl-comment">*/</span><span class="hl-code"> 
     </span><span class="hl-types">int</span><span class="hl-code"> </span><span class="hl-identifier">b</span><span class="hl-code"> = </span><span class="hl-number">13</span><span class="hl-code">; </span><span class="hl-comment">/*</span><span class="hl-comment"> 13 = 0000 1101 </span><span class="hl-comment">*/</span><span class="hl-code">
     </span><span class="hl-types">int</span><span class="hl-code"> </span><span class="hl-identifier">c</span><span class="hl-code"> = </span><span class="hl-number">0</span><span class="hl-code">;
     </span><span class="hl-identifier">c</span><span class="hl-code"> = </span><span class="hl-identifier">a</span><span class="hl-code"> &amp; </span><span class="hl-identifier">b</span><span class="hl-code">;       </span><span class="hl-comment">/*</span><span class="hl-comment"> 12 = 0000 1100 </span><span class="hl-comment">*/</span><span class="hl-code">
     </span><span class="hl-identifier">System</span><span class="hl-code">.</span><span class="hl-identifier">out</span><span class="hl-code">.</span><span class="hl-identifier">println</span><span class="hl-brackets">(</span><span class="hl-quotes">&quot;</span><span class="hl-string">a &amp; b = </span><span class="hl-quotes">&quot;</span><span class="hl-code"> + </span><span class="hl-identifier">c</span><span class="hl-code"> </span><span class="hl-brackets">)</span><span class="hl-code">;
 
     </span><span class="hl-identifier">c</span><span class="hl-code"> = </span><span class="hl-identifier">a</span><span class="hl-code"> | </span><span class="hl-identifier">b</span><span class="hl-code">;       </span><span class="hl-comment">/*</span><span class="hl-comment"> 61 = 0011 1101 </span><span class="hl-comment">*/</span><span class="hl-code">
     </span><span class="hl-identifier">System</span><span class="hl-code">.</span><span class="hl-identifier">out</span><span class="hl-code">.</span><span class="hl-identifier">println</span><span class="hl-brackets">(</span><span class="hl-quotes">&quot;</span><span class="hl-string">a | b = </span><span class="hl-quotes">&quot;</span><span class="hl-code"> + </span><span class="hl-identifier">c</span><span class="hl-code"> </span><span class="hl-brackets">)</span><span class="hl-code">;
 
     </span><span class="hl-identifier">c</span><span class="hl-code"> = </span><span class="hl-identifier">a</span><span class="hl-code"> ^ </span><span class="hl-identifier">b</span><span class="hl-code">;       </span><span class="hl-comment">/*</span><span class="hl-comment"> 49 = 0011 0001 </span><span class="hl-comment">*/</span><span class="hl-code">
     </span><span class="hl-identifier">System</span><span class="hl-code">.</span><span class="hl-identifier">out</span><span class="hl-code">.</span><span class="hl-identifier">println</span><span class="hl-brackets">(</span><span class="hl-quotes">&quot;</span><span class="hl-string">a ^ b = </span><span class="hl-quotes">&quot;</span><span class="hl-code"> + </span><span class="hl-identifier">c</span><span class="hl-code"> </span><span class="hl-brackets">)</span><span class="hl-code">;
 
     </span><span class="hl-identifier">c</span><span class="hl-code"> = ~</span><span class="hl-identifier">a</span><span class="hl-code">;          </span><span class="hl-comment">/*</span><span class="hl-comment">-61 = 1100 0011 </span><span class="hl-comment">*/</span><span class="hl-code">
     </span><span class="hl-identifier">System</span><span class="hl-code">.</span><span class="hl-identifier">out</span><span class="hl-code">.</span><span class="hl-identifier">println</span><span class="hl-brackets">(</span><span class="hl-quotes">&quot;</span><span class="hl-string">~a = </span><span class="hl-quotes">&quot;</span><span class="hl-code"> + </span><span class="hl-identifier">c</span><span class="hl-code"> </span><span class="hl-brackets">)</span><span class="hl-code">;
 
     </span><span class="hl-identifier">c</span><span class="hl-code"> = </span><span class="hl-identifier">a</span><span class="hl-code"> &lt;&lt; </span><span class="hl-number">2</span><span class="hl-code">;     </span><span class="hl-comment">/*</span><span class="hl-comment"> 240 = 1111 0000 </span><span class="hl-comment">*/</span><span class="hl-code">
     </span><span class="hl-identifier">System</span><span class="hl-code">.</span><span class="hl-identifier">out</span><span class="hl-code">.</span><span class="hl-identifier">println</span><span class="hl-brackets">(</span><span class="hl-quotes">&quot;</span><span class="hl-string">a &lt;&lt; 2 = </span><span class="hl-quotes">&quot;</span><span class="hl-code"> + </span><span class="hl-identifier">c</span><span class="hl-code"> </span><span class="hl-brackets">)</span><span class="hl-code">;
 
     </span><span class="hl-identifier">c</span><span class="hl-code"> = </span><span class="hl-identifier">a</span><span class="hl-code"> &gt;&gt; </span><span class="hl-number">2</span><span class="hl-code">;     </span><span class="hl-comment">/*</span><span class="hl-comment"> 15 = 1111 </span><span class="hl-comment">*/</span><span class="hl-code">
     </span><span class="hl-identifier">System</span><span class="hl-code">.</span><span class="hl-identifier">out</span><span class="hl-code">.</span><span class="hl-identifier">println</span><span class="hl-brackets">(</span><span class="hl-quotes">&quot;</span><span class="hl-string">a &gt;&gt; 2  = </span><span class="hl-quotes">&quot;</span><span class="hl-code"> + </span><span class="hl-identifier">c</span><span class="hl-code"> </span><span class="hl-brackets">)</span><span class="hl-code">;
  
     </span><span class="hl-identifier">c</span><span class="hl-code"> = </span><span class="hl-identifier">a</span><span class="hl-code"> &gt;&gt;&gt; </span><span class="hl-number">2</span><span class="hl-code">;     </span><span class="hl-comment">/*</span><span class="hl-comment"> 15 = 0000 1111 </span><span class="hl-comment">*/</span><span class="hl-code">
     </span><span class="hl-identifier">System</span><span class="hl-code">.</span><span class="hl-identifier">out</span><span class="hl-code">.</span><span class="hl-identifier">println</span><span class="hl-brackets">(</span><span class="hl-quotes">&quot;</span><span class="hl-string">a &gt;&gt;&gt; 2 = </span><span class="hl-quotes">&quot;</span><span class="hl-code"> + </span><span class="hl-identifier">c</span><span class="hl-code"> </span><span class="hl-brackets">)</span><span class="hl-code">;
  </span><span class="hl-brackets">}</span><span class="hl-code">
</span><span class="hl-brackets">}</span><span class="hl-code"> </span></div>
</div>
</div>
<p>以上实例编译运行结果如下：</p>

<pre>
a &amp; b = 12
a | b = 61
a ^ b = 49
~a = -61
a &lt;&lt; 2 = 240
a &gt;&gt; 2  = 15
a &gt;&gt;&gt; 2 = 15
</pre>
<hr><h2>逻辑运算符</h2>
<p>下表列出了逻辑运算符的基本运算，假设布尔变量A为真，变量B为假</p>
<table class="reference">
	<tbody>
		<tr>
			<th style="width:37px;">
				操作符</th>
			<th style="width:433px;">
				描述</th>
			<th style="width:106px;">
				例子</th>
		</tr>
		<tr>
			<td style="width:37px;">
				&amp;&amp;</td>
			<td style="width:433px;">
				称为逻辑与运算符。当且仅当两个操作数都为真，条件才为真。</td>
			<td style="width:106px;">
				（A &amp;&amp; B）为假。</td>
		</tr>
		<tr>
			<td style="width:37px;">
				| |</td>
			<td style="width:433px;">
				称为逻辑或操作符。如果任何两个操作数任何一个为真，条件为真。</td>
			<td style="width:106px;">
				（A | | B）为真。</td>
		</tr>
		<tr>
			<td style="width:37px;">
				！</td>
			<td style="width:433px;">
				称为逻辑非运算符。用来反转操作数的逻辑状态。如果条件为true，则逻辑非运算符将得到false。</td>
			<td style="width:106px;">
				！（A &amp;&amp; B）为真。</td>
		</tr>
	</tbody>
</table>
<h3>实例</h3>
<p>下面的简单示例程序演示了逻辑运算符。复制并粘贴下面的Java程序并保存为Test.java文件，然后编译并运行这个程序：</p>
<div class="example"> 
<h2 class="example">实例</h2> 
<div class="example_code">
<div class="hl-main"><span class="hl-reserved">public</span><span class="hl-code"> </span><span class="hl-reserved">class</span><span class="hl-code"> </span><span class="hl-identifier">Test</span><span class="hl-code"> </span><span class="hl-brackets">{</span><span class="hl-code">
  </span><span class="hl-reserved">public</span><span class="hl-code"> </span><span class="hl-types">static</span><span class="hl-code"> </span><span class="hl-types">void</span><span class="hl-code"> </span><span class="hl-identifier">main</span><span class="hl-brackets">(</span><span class="hl-identifier">String</span><span class="hl-brackets">[</span><span class="hl-brackets">]</span><span class="hl-code"> </span><span class="hl-identifier">args</span><span class="hl-brackets">)</span><span class="hl-code"> </span><span class="hl-brackets">{</span><span class="hl-code">
     </span><span class="hl-types">boolean</span><span class="hl-code"> </span><span class="hl-identifier">a</span><span class="hl-code"> = </span><span class="hl-reserved">true</span><span class="hl-code">;
     </span><span class="hl-types">boolean</span><span class="hl-code"> </span><span class="hl-identifier">b</span><span class="hl-code"> = </span><span class="hl-reserved">false</span><span class="hl-code">;
     </span><span class="hl-identifier">System</span><span class="hl-code">.</span><span class="hl-identifier">out</span><span class="hl-code">.</span><span class="hl-identifier">println</span><span class="hl-brackets">(</span><span class="hl-quotes">&quot;</span><span class="hl-string">a &amp;&amp; b = </span><span class="hl-quotes">&quot;</span><span class="hl-code"> + </span><span class="hl-brackets">(</span><span class="hl-identifier">a</span><span class="hl-code">&amp;&amp;</span><span class="hl-identifier">b</span><span class="hl-brackets">)</span><span class="hl-brackets">)</span><span class="hl-code">;
     </span><span class="hl-identifier">System</span><span class="hl-code">.</span><span class="hl-identifier">out</span><span class="hl-code">.</span><span class="hl-identifier">println</span><span class="hl-brackets">(</span><span class="hl-quotes">&quot;</span><span class="hl-string">a || b = </span><span class="hl-quotes">&quot;</span><span class="hl-code"> + </span><span class="hl-brackets">(</span><span class="hl-identifier">a</span><span class="hl-code">||</span><span class="hl-identifier">b</span><span class="hl-brackets">)</span><span class="hl-code"> </span><span class="hl-brackets">)</span><span class="hl-code">;
     </span><span class="hl-identifier">System</span><span class="hl-code">.</span><span class="hl-identifier">out</span><span class="hl-code">.</span><span class="hl-identifier">println</span><span class="hl-brackets">(</span><span class="hl-quotes">&quot;</span><span class="hl-string">!(a &amp;&amp; b) = </span><span class="hl-quotes">&quot;</span><span class="hl-code"> + !</span><span class="hl-brackets">(</span><span class="hl-identifier">a</span><span class="hl-code"> &amp;&amp; </span><span class="hl-identifier">b</span><span class="hl-brackets">)</span><span class="hl-brackets">)</span><span class="hl-code">;
  </span><span class="hl-brackets">}</span><span class="hl-code">
</span><span class="hl-brackets">}</span></div>
</div>
</div>
<p>以上实例编译运行结果如下：</p>
<pre>
a &amp;&amp; b = false
a || b = true
!(a &amp;&amp; b) = true
</pre>
<h3>短路逻辑运算符</h3>
<p>当使用与逻辑运算符时，在两个操作数都为true时，结果才为true，但是当得到第一个操作为false时，其结果就必定是false，这时候就不会再判断第二个操作了。</p>
<div class="example"> 
<h2 class="example">实例</h2> 
<div class="example_code">
<div class="hl-main"><span class="hl-reserved">public</span><span class="hl-code"> </span><span class="hl-reserved">class</span><span class="hl-code"> </span><span class="hl-identifier">LuoJi</span><span class="hl-brackets">{</span><span class="hl-code">
    </span><span class="hl-reserved">public</span><span class="hl-code"> </span><span class="hl-types">static</span><span class="hl-code"> </span><span class="hl-types">void</span><span class="hl-code"> </span><span class="hl-identifier">main</span><span class="hl-brackets">(</span><span class="hl-identifier">String</span><span class="hl-brackets">[</span><span class="hl-brackets">]</span><span class="hl-code"> </span><span class="hl-identifier">args</span><span class="hl-brackets">)</span><span class="hl-brackets">{</span><span class="hl-code">
        </span><span class="hl-types">int</span><span class="hl-code"> </span><span class="hl-identifier">a</span><span class="hl-code"> = </span><span class="hl-number">5</span><span class="hl-code">;</span><span class="hl-comment">//</span><span class="hl-comment">定义一个变量；</span><span class="hl-comment"></span><span class="hl-code">
        </span><span class="hl-types">boolean</span><span class="hl-code"> </span><span class="hl-identifier">b</span><span class="hl-code"> = </span><span class="hl-brackets">(</span><span class="hl-identifier">a</span><span class="hl-code">&lt;</span><span class="hl-number">4</span><span class="hl-brackets">)</span><span class="hl-code">&amp;&amp;</span><span class="hl-brackets">(</span><span class="hl-identifier">a</span><span class="hl-code">++&lt;</span><span class="hl-number">10</span><span class="hl-brackets">)</span><span class="hl-code">;
        </span><span class="hl-identifier">System</span><span class="hl-code">.</span><span class="hl-identifier">out</span><span class="hl-code">.</span><span class="hl-identifier">println</span><span class="hl-brackets">(</span><span class="hl-quotes">&quot;</span><span class="hl-string">使用短路逻辑运算符的结果为</span><span class="hl-quotes">&quot;</span><span class="hl-code">+</span><span class="hl-identifier">b</span><span class="hl-brackets">)</span><span class="hl-code">;
        </span><span class="hl-identifier">System</span><span class="hl-code">.</span><span class="hl-identifier">out</span><span class="hl-code">.</span><span class="hl-identifier">println</span><span class="hl-brackets">(</span><span class="hl-quotes">&quot;</span><span class="hl-string">a的结果为</span><span class="hl-quotes">&quot;</span><span class="hl-code">+</span><span class="hl-identifier">a</span><span class="hl-brackets">)</span><span class="hl-code">;
    </span><span class="hl-brackets">}</span><span class="hl-code">
</span><span class="hl-brackets">}</span></div>
</div>
</div>
<p>运行结果为：</p>
<pre>使用短路逻辑运算符的结果为false
a的结果为5</pre>


<blockquote><p><b>解析：
</b>
该程序使用到了短路逻辑运算符(&&)，首先判断 a<4 的结果为 false，则 b 的结果必定是 false，所以不再执行第二个操作 a++&lt;10 的判断，所以 a 的值为 5。
</p></blockquote>


<hr><h2>赋值运算符</h2>
<p>

下面是Java语言支持的赋值运算符：</p>
<table class="reference">
	<tbody>
		<tr>
			<th style="width:46px;">
				操作符</th>
			<th style="width:376px;">
				描述</th>
			<th style="width:154px;">
				例子</th>
		</tr>
		<tr>
			<td style="width:46px;">
				=</td>
			<td style="width:376px;">
				简单的赋值运算符，将右操作数的值赋给左侧操作数</td>
			<td style="width:154px;">
				C = A + B将把A + B得到的值赋给C</td>
		</tr>
		<tr>
			<td style="width:46px;">
				+ =</td>
			<td style="width:376px;">
				加和赋值操作符，它把左操作数和右操作数相加赋值给左操作数</td>
			<td style="width:154px;">
				C + = A等价于C = C + A</td>
		</tr>
		<tr>
			<td style="width:46px;">
				- =</td>
			<td style="width:376px;">
				减和赋值操作符，它把左操作数和右操作数相减赋值给左操作数</td>
			<td style="width:154px;">
				C - = A等价于C = C - A</td>
		</tr>
		<tr>
			<td style="width:46px;">
				* =</td>
			<td style="width:376px;">
				乘和赋值操作符，它把左操作数和右操作数相乘赋值给左操作数</td>
			<td style="width:154px;">
				C * = A等价于C = C * A</td>
		</tr>
		<tr>
			<td style="width:46px;">
				/ =</td>
			<td style="width:376px;">
				除和赋值操作符，它把左操作数和右操作数相除赋值给左操作数</td>
			<td style="width:154px;">
				C / = A，C 与 A 同类型时等价于 C = C / A</td>
		</tr>
		<tr>
			<td style="width:46px;">
				（％）=</td>
			<td style="width:376px;">
				取模和赋值操作符，它把左操作数和右操作数取模后赋值给左操作数</td>
			<td style="width:154px;">
				C％= A等价于C = C％A</td>
		</tr>
		<tr>
			<td style="width:46px;">
				&lt;&lt; =</td>
			<td style="width:376px;">
				左移位赋值运算符</td>
			<td style="width:154px;">
				C &lt;&lt; = 2等价于C = C &lt;&lt; 2</td>
		</tr>
		<tr>
			<td style="width:46px;">
				&gt;&gt; =</td>
			<td style="width:376px;">
				右移位赋值运算符</td>
			<td style="width:154px;">
				C &gt;&gt; = 2等价于C = C &gt;&gt; 2</td>
		</tr>
		<tr>
			<td style="width:46px;">
				＆=</td>
			<td style="width:376px;">
				按位与赋值运算符</td>
			<td style="width:154px;">
				C＆= 2等价于C = C＆2</td>
		</tr>
		<tr>
			<td style="width:46px;">
				^ =</td>
			<td style="width:376px;">
				按位异或赋值操作符</td>
			<td style="width:154px;">
				C ^ = 2等价于C = C ^ 2</td>
		</tr>
		<tr>
			<td style="width:46px;">
				| =</td>
			<td style="width:376px;">
				按位或赋值操作符</td>
			<td style="width:154px;">
				C | = 2等价于C = C | 2</td>
		</tr>
	</tbody>
</table>
<h3>实例</h3>
<p>下面的简单示例程序演示了赋值运算符。复制并粘贴下面的Java程序并保存为Test.java文件，然后编译并运行这个程序：</p>
<div class="example">
<h2 class="example">Test.java 文件代码：</h2> 
<div class="example_code">
<div class="hl-main"><span class="hl-reserved">public</span><span class="hl-code"> </span><span class="hl-reserved">class</span><span class="hl-code"> </span><span class="hl-identifier">Test</span><span class="hl-code"> </span><span class="hl-brackets">{</span><span class="hl-code">
    </span><span class="hl-reserved">public</span><span class="hl-code"> </span><span class="hl-types">static</span><span class="hl-code"> </span><span class="hl-types">void</span><span class="hl-code"> </span><span class="hl-identifier">main</span><span class="hl-brackets">(</span><span class="hl-identifier">String</span><span class="hl-brackets">[</span><span class="hl-brackets">]</span><span class="hl-code"> </span><span class="hl-identifier">args</span><span class="hl-brackets">)</span><span class="hl-code"> </span><span class="hl-brackets">{</span><span class="hl-code">
        </span><span class="hl-types">int</span><span class="hl-code"> </span><span class="hl-identifier">a</span><span class="hl-code"> = </span><span class="hl-number">10</span><span class="hl-code">;
        </span><span class="hl-types">int</span><span class="hl-code"> </span><span class="hl-identifier">b</span><span class="hl-code"> = </span><span class="hl-number">20</span><span class="hl-code">;
        </span><span class="hl-types">int</span><span class="hl-code"> </span><span class="hl-identifier">c</span><span class="hl-code"> = </span><span class="hl-number">0</span><span class="hl-code">;
        </span><span class="hl-identifier">c</span><span class="hl-code"> = </span><span class="hl-identifier">a</span><span class="hl-code"> + </span><span class="hl-identifier">b</span><span class="hl-code">;
        </span><span class="hl-identifier">System</span><span class="hl-code">.</span><span class="hl-identifier">out</span><span class="hl-code">.</span><span class="hl-identifier">println</span><span class="hl-brackets">(</span><span class="hl-quotes">&quot;</span><span class="hl-string">c = a + b = </span><span class="hl-quotes">&quot;</span><span class="hl-code"> + </span><span class="hl-identifier">c</span><span class="hl-code"> </span><span class="hl-brackets">)</span><span class="hl-code">;
        </span><span class="hl-identifier">c</span><span class="hl-code"> += </span><span class="hl-identifier">a</span><span class="hl-code"> ;
        </span><span class="hl-identifier">System</span><span class="hl-code">.</span><span class="hl-identifier">out</span><span class="hl-code">.</span><span class="hl-identifier">println</span><span class="hl-brackets">(</span><span class="hl-quotes">&quot;</span><span class="hl-string">c += a  = </span><span class="hl-quotes">&quot;</span><span class="hl-code"> + </span><span class="hl-identifier">c</span><span class="hl-code"> </span><span class="hl-brackets">)</span><span class="hl-code">;
        </span><span class="hl-identifier">c</span><span class="hl-code"> -= </span><span class="hl-identifier">a</span><span class="hl-code"> ;
        </span><span class="hl-identifier">System</span><span class="hl-code">.</span><span class="hl-identifier">out</span><span class="hl-code">.</span><span class="hl-identifier">println</span><span class="hl-brackets">(</span><span class="hl-quotes">&quot;</span><span class="hl-string">c -= a = </span><span class="hl-quotes">&quot;</span><span class="hl-code"> + </span><span class="hl-identifier">c</span><span class="hl-code"> </span><span class="hl-brackets">)</span><span class="hl-code">;
        </span><span class="hl-identifier">c</span><span class="hl-code"> *= </span><span class="hl-identifier">a</span><span class="hl-code"> ;
        </span><span class="hl-identifier">System</span><span class="hl-code">.</span><span class="hl-identifier">out</span><span class="hl-code">.</span><span class="hl-identifier">println</span><span class="hl-brackets">(</span><span class="hl-quotes">&quot;</span><span class="hl-string">c *= a = </span><span class="hl-quotes">&quot;</span><span class="hl-code"> + </span><span class="hl-identifier">c</span><span class="hl-code"> </span><span class="hl-brackets">)</span><span class="hl-code">;
        </span><span class="hl-identifier">a</span><span class="hl-code"> = </span><span class="hl-number">10</span><span class="hl-code">;
        </span><span class="hl-identifier">c</span><span class="hl-code"> = </span><span class="hl-number">15</span><span class="hl-code">;
        </span><span class="hl-identifier">c</span><span class="hl-code"> /= </span><span class="hl-identifier">a</span><span class="hl-code"> ;
        </span><span class="hl-identifier">System</span><span class="hl-code">.</span><span class="hl-identifier">out</span><span class="hl-code">.</span><span class="hl-identifier">println</span><span class="hl-brackets">(</span><span class="hl-quotes">&quot;</span><span class="hl-string">c /= a = </span><span class="hl-quotes">&quot;</span><span class="hl-code"> + </span><span class="hl-identifier">c</span><span class="hl-code"> </span><span class="hl-brackets">)</span><span class="hl-code">;
        </span><span class="hl-identifier">a</span><span class="hl-code"> = </span><span class="hl-number">10</span><span class="hl-code">;
        </span><span class="hl-identifier">c</span><span class="hl-code"> = </span><span class="hl-number">15</span><span class="hl-code">;
        </span><span class="hl-identifier">c</span><span class="hl-code"> %= </span><span class="hl-identifier">a</span><span class="hl-code"> ;
        </span><span class="hl-identifier">System</span><span class="hl-code">.</span><span class="hl-identifier">out</span><span class="hl-code">.</span><span class="hl-identifier">println</span><span class="hl-brackets">(</span><span class="hl-quotes">&quot;</span><span class="hl-string">c %= a  = </span><span class="hl-quotes">&quot;</span><span class="hl-code"> + </span><span class="hl-identifier">c</span><span class="hl-code"> </span><span class="hl-brackets">)</span><span class="hl-code">;
        </span><span class="hl-identifier">c</span><span class="hl-code"> &lt;&lt;= </span><span class="hl-number">2</span><span class="hl-code"> ;
        </span><span class="hl-identifier">System</span><span class="hl-code">.</span><span class="hl-identifier">out</span><span class="hl-code">.</span><span class="hl-identifier">println</span><span class="hl-brackets">(</span><span class="hl-quotes">&quot;</span><span class="hl-string">c &lt;&lt;= 2 = </span><span class="hl-quotes">&quot;</span><span class="hl-code"> + </span><span class="hl-identifier">c</span><span class="hl-code"> </span><span class="hl-brackets">)</span><span class="hl-code">;
        </span><span class="hl-identifier">c</span><span class="hl-code"> &gt;&gt;= </span><span class="hl-number">2</span><span class="hl-code"> ;
        </span><span class="hl-identifier">System</span><span class="hl-code">.</span><span class="hl-identifier">out</span><span class="hl-code">.</span><span class="hl-identifier">println</span><span class="hl-brackets">(</span><span class="hl-quotes">&quot;</span><span class="hl-string">c &gt;&gt;= 2 = </span><span class="hl-quotes">&quot;</span><span class="hl-code"> + </span><span class="hl-identifier">c</span><span class="hl-code"> </span><span class="hl-brackets">)</span><span class="hl-code">;
        </span><span class="hl-identifier">c</span><span class="hl-code"> &gt;&gt;= </span><span class="hl-number">2</span><span class="hl-code"> ;
        </span><span class="hl-identifier">System</span><span class="hl-code">.</span><span class="hl-identifier">out</span><span class="hl-code">.</span><span class="hl-identifier">println</span><span class="hl-brackets">(</span><span class="hl-quotes">&quot;</span><span class="hl-string">c &gt;&gt;= 2 = </span><span class="hl-quotes">&quot;</span><span class="hl-code"> + </span><span class="hl-identifier">c</span><span class="hl-code"> </span><span class="hl-brackets">)</span><span class="hl-code">;
        </span><span class="hl-identifier">c</span><span class="hl-code"> &amp;= </span><span class="hl-identifier">a</span><span class="hl-code"> ;
        </span><span class="hl-identifier">System</span><span class="hl-code">.</span><span class="hl-identifier">out</span><span class="hl-code">.</span><span class="hl-identifier">println</span><span class="hl-brackets">(</span><span class="hl-quotes">&quot;</span><span class="hl-string">c &amp;= a  = </span><span class="hl-quotes">&quot;</span><span class="hl-code"> + </span><span class="hl-identifier">c</span><span class="hl-code"> </span><span class="hl-brackets">)</span><span class="hl-code">;
        </span><span class="hl-identifier">c</span><span class="hl-code"> ^= </span><span class="hl-identifier">a</span><span class="hl-code"> ;
        </span><span class="hl-identifier">System</span><span class="hl-code">.</span><span class="hl-identifier">out</span><span class="hl-code">.</span><span class="hl-identifier">println</span><span class="hl-brackets">(</span><span class="hl-quotes">&quot;</span><span class="hl-string">c ^= a   = </span><span class="hl-quotes">&quot;</span><span class="hl-code"> + </span><span class="hl-identifier">c</span><span class="hl-code"> </span><span class="hl-brackets">)</span><span class="hl-code">;
        </span><span class="hl-identifier">c</span><span class="hl-code"> |= </span><span class="hl-identifier">a</span><span class="hl-code"> ;
        </span><span class="hl-identifier">System</span><span class="hl-code">.</span><span class="hl-identifier">out</span><span class="hl-code">.</span><span class="hl-identifier">println</span><span class="hl-brackets">(</span><span class="hl-quotes">&quot;</span><span class="hl-string">c |= a   = </span><span class="hl-quotes">&quot;</span><span class="hl-code"> + </span><span class="hl-identifier">c</span><span class="hl-code"> </span><span class="hl-brackets">)</span><span class="hl-code">;
    </span><span class="hl-brackets">}</span><span class="hl-code">
</span><span class="hl-brackets">}</span></div>
</div>
</div>
<p>以上实例编译运行结果如下：</p>
<pre>
c = a + b = 30
c += a&nbsp; = 40
c -= a = 30
c *= a = 300
c /= a = 1
c %= a&nbsp; = 5
c &lt;&lt;= 2 = 20
c &gt;&gt;= 2 = 5
c &gt;&gt;= 2 = 1
c &amp;= a&nbsp; = 0
c ^= a&nbsp;&nbsp; = 10
c |= a&nbsp;&nbsp; = 10
</pre>
<hr><h2>条件运算符（?:）</h2>
<p>条件运算符也被称为三元运算符。该运算符有3个操作数，并且需要判断布尔表达式的值。该运算符的主要是决定哪个值应该赋值给变量。</p>
<pre>
variable x = (expression) ? value if true : value if false
</pre>
<h3>实例</h3>
<div class="example">
<h2 class="example">Test.java 文件代码：</h2> 
<div class="example_code">
<div class="hl-main"><span class="hl-reserved">public</span><span class="hl-code"> </span><span class="hl-reserved">class</span><span class="hl-code"> </span><span class="hl-identifier">Test</span><span class="hl-code"> </span><span class="hl-brackets">{</span><span class="hl-code">
   </span><span class="hl-reserved">public</span><span class="hl-code"> </span><span class="hl-types">static</span><span class="hl-code"> </span><span class="hl-types">void</span><span class="hl-code"> </span><span class="hl-identifier">main</span><span class="hl-brackets">(</span><span class="hl-identifier">String</span><span class="hl-brackets">[</span><span class="hl-brackets">]</span><span class="hl-code"> </span><span class="hl-identifier">args</span><span class="hl-brackets">)</span><span class="hl-brackets">{</span><span class="hl-code">
      </span><span class="hl-types">int</span><span class="hl-code"> </span><span class="hl-identifier">a</span><span class="hl-code"> , </span><span class="hl-identifier">b</span><span class="hl-code">;
      </span><span class="hl-identifier">a</span><span class="hl-code"> = </span><span class="hl-number">10</span><span class="hl-code">;
      </span><span class="hl-comment">//</span><span class="hl-comment"> 如果 a 等于 1 成立，则设置 b 为 20，否则为 30</span><span class="hl-comment"></span><span class="hl-code">
      </span><span class="hl-identifier">b</span><span class="hl-code"> = </span><span class="hl-brackets">(</span><span class="hl-identifier">a</span><span class="hl-code"> == </span><span class="hl-number">1</span><span class="hl-brackets">)</span><span class="hl-code"> ? </span><span class="hl-number">20</span><span class="hl-code"> : </span><span class="hl-number">30</span><span class="hl-code">;
      </span><span class="hl-identifier">System</span><span class="hl-code">.</span><span class="hl-identifier">out</span><span class="hl-code">.</span><span class="hl-identifier">println</span><span class="hl-brackets">(</span><span class="hl-code"> </span><span class="hl-quotes">&quot;</span><span class="hl-string">Value of b is : </span><span class="hl-quotes">&quot;</span><span class="hl-code"> +  </span><span class="hl-identifier">b</span><span class="hl-code"> </span><span class="hl-brackets">)</span><span class="hl-code">;
 
      </span><span class="hl-comment">//</span><span class="hl-comment"> 如果 a 等于 10 成立，则设置 b 为 20，否则为 30</span><span class="hl-comment"></span><span class="hl-code">
      </span><span class="hl-identifier">b</span><span class="hl-code"> = </span><span class="hl-brackets">(</span><span class="hl-identifier">a</span><span class="hl-code"> == </span><span class="hl-number">10</span><span class="hl-brackets">)</span><span class="hl-code"> ? </span><span class="hl-number">20</span><span class="hl-code"> : </span><span class="hl-number">30</span><span class="hl-code">;
      </span><span class="hl-identifier">System</span><span class="hl-code">.</span><span class="hl-identifier">out</span><span class="hl-code">.</span><span class="hl-identifier">println</span><span class="hl-brackets">(</span><span class="hl-code"> </span><span class="hl-quotes">&quot;</span><span class="hl-string">Value of b is : </span><span class="hl-quotes">&quot;</span><span class="hl-code"> + </span><span class="hl-identifier">b</span><span class="hl-code"> </span><span class="hl-brackets">)</span><span class="hl-code">;
   </span><span class="hl-brackets">}</span><span class="hl-code">
</span><span class="hl-brackets">}</span></div>
</div>
</div>
<p>以上实例编译运行结果如下：</p>
<pre>
Value of b is : 30
Value of b is : 20
</pre>

<hr><h2>instanceof 运算符</h2>

<p>该运算符用于操作对象实例，检查该对象是否是一个特定类型（类类型或接口类型）。</p>
<p>instanceof运算符使用格式如下：</p>
<pre>
( Object reference variable ) instanceof  (class/interface type)
</pre>
<p>
如果运算符左侧变量所指的对象，是操作符右侧类或接口(class/interface)的一个对象，那么结果为真。
</p><p>
下面是一个例子：</p>
<pre>
String name = "James";
boolean result = name instanceof String; // 由于 name 是 String 类型，所以返回真
</pre>
<p>如果被比较的对象兼容于右侧类型，该运算符仍然返回 true。</p>
<p>看下面的例子：</p>
<div class="example">
<div class="example_code">
<div class="hl-main"><span class="hl-reserved">class</span><span class="hl-code"> </span><span class="hl-identifier">Vehicle</span><span class="hl-code"> </span><span class="hl-brackets">{</span><span class="hl-brackets">}</span><span class="hl-code">
 
</span><span class="hl-reserved">public</span><span class="hl-code"> </span><span class="hl-reserved">class</span><span class="hl-code"> </span><span class="hl-identifier">Car</span><span class="hl-code"> </span><span class="hl-reserved">extends</span><span class="hl-code"> </span><span class="hl-identifier">Vehicle</span><span class="hl-code"> </span><span class="hl-brackets">{</span><span class="hl-code">
   </span><span class="hl-reserved">public</span><span class="hl-code"> </span><span class="hl-types">static</span><span class="hl-code"> </span><span class="hl-types">void</span><span class="hl-code"> </span><span class="hl-identifier">main</span><span class="hl-brackets">(</span><span class="hl-identifier">String</span><span class="hl-brackets">[</span><span class="hl-brackets">]</span><span class="hl-code"> </span><span class="hl-identifier">args</span><span class="hl-brackets">)</span><span class="hl-brackets">{</span><span class="hl-code">
      </span><span class="hl-identifier">Vehicle</span><span class="hl-code"> </span><span class="hl-identifier">a</span><span class="hl-code"> = </span><span class="hl-reserved">new</span><span class="hl-code"> </span><span class="hl-identifier">Car</span><span class="hl-brackets">(</span><span class="hl-brackets">)</span><span class="hl-code">;
      </span><span class="hl-types">boolean</span><span class="hl-code"> </span><span class="hl-identifier">result</span><span class="hl-code"> =  </span><span class="hl-identifier">a</span><span class="hl-code"> </span><span class="hl-reserved">instanceof</span><span class="hl-code"> </span><span class="hl-identifier">Car</span><span class="hl-code">;
      </span><span class="hl-identifier">System</span><span class="hl-code">.</span><span class="hl-identifier">out</span><span class="hl-code">.</span><span class="hl-identifier">println</span><span class="hl-brackets">(</span><span class="hl-code"> </span><span class="hl-identifier">result</span><span class="hl-brackets">)</span><span class="hl-code">;
   </span><span class="hl-brackets">}</span><span class="hl-code">
</span><span class="hl-brackets">}</span></div>
</div>
</div>
<p>以上实例编译运行结果如下：</p>
<pre>true</pre>
<hr><h2>Java运算符优先级</h2>
<p>当多个运算符出现在一个表达式中，谁先谁后呢？这就涉及到运算符的优先级别的问题。在一个多运算符的表达式中，运算符优先级不同会导致最后得出的结果差别甚大。</p><p>例如，（1+3）＋（3+2）*2，这个表达式如果按加号最优先计算，答案就是 18，如果按照乘号最优先，答案则是 14。
</p><p>再如，x = 7 + 3 * 2;这里x得到13，而不是20，因为乘法运算符比加法运算符有较高的优先级，所以先计算3 * 2得到6，然后再加7。
</p><p>下表中具有最高优先级的运算符在的表的最上面，最低优先级的在表的底部。</p>
<table class="reference">
	<tbody>
		<tr>
			<th style="width:66px;">
				类别 </th>
			<th style="width:274px;">
				操作符</th>
			<th style="width:132px;">
				关联性 </th>
		</tr>
		<tr>
			<td style="width:66px;">
				后缀</td>
			<td style="width:274px;">
				() [] . (点操作符)</td>
			<td style="width:132px;">
				左到右</td>
		</tr>
<tr>
			<td style="width:66px;">
				一元</td>
			<td style="width:274px;">
				expr++  expr--</td>
			<td style="width:132px;">
				从左到右</td>
		</tr>
		<tr>
			<td style="width:66px;">
				一元</td>
			<td style="width:274px;">
				++expr --expr + - ～ ！</td>
			<td style="width:132px;">
				从右到左</td>
		</tr>
		<tr>
			<td style="width:66px;">
				乘性&nbsp;</td>
			<td style="width:274px;">
				* /％</td>
			<td style="width:132px;">
				左到右</td>
		</tr>
		<tr>
			<td style="width:66px;">
				加性&nbsp;</td>
			<td style="width:274px;">
				+ -</td>
			<td style="width:132px;">
				左到右</td>
		</tr>
		<tr>
			<td style="width:66px;">
				移位&nbsp;</td>
			<td style="width:274px;">
				&gt;&gt; &gt;&gt;&gt; &nbsp;&lt;&lt;&nbsp;</td>
			<td style="width:132px;">
				左到右</td>
		</tr>
		<tr>
			<td style="width:66px;">
				关系&nbsp;</td>
			<td style="width:274px;">
				&gt;  &gt;=  &lt;  &lt;=&nbsp;</td>
			<td style="width:132px;">
				左到右</td>
		</tr>
		<tr>
			<td style="width:66px;">
				相等&nbsp;</td>
			<td style="width:274px;">
				==&nbsp; !=</td>
			<td style="width:132px;">
				左到右</td>
		</tr>
		<tr>
			<td style="width:66px;">
				按位与</td>
			<td style="width:274px;">
				＆</td>
			<td style="width:132px;">
				左到右</td>
		</tr>
		<tr>
			<td style="width:66px;">
				按位异或</td>
			<td style="width:274px;">
				^</td>
			<td style="width:132px;">
				左到右</td>
		</tr>
		<tr>
			<td style="width:66px;">
				按位或</td>
			<td style="width:274px;">
				|</td>
			<td style="width:132px;">
				左到右</td>
		</tr>
		<tr>
			<td style="width:66px;">
				逻辑与</td>
			<td style="width:274px;">
				&amp;&amp;</td>
			<td style="width:132px;">
				左到右</td>
		</tr>
		<tr>
			<td style="width:66px;">
				逻辑或</td>
			<td style="width:274px;">
				| |</td>
			<td style="width:132px;">
				左到右</td>
		</tr>
		<tr>
			<td style="width:66px;">
				条件</td>
			<td style="width:274px;">
				？：</td>
			<td style="width:132px;">
				从右到左</td>
		</tr>
		<tr>
			<td style="width:66px;">
				赋值</td>
			<td style="width:274px;">
				= + = - = * = / =％= &gt;&gt; = &lt;&lt; =＆= ^ = | =</td>
			<td style="width:132px;">
				从右到左</td>
		</tr>
		<tr>
			<td style="width:66px;">
				逗号</td>
			<td style="width:274px;">
				，</td>
			<td style="width:132px;">
				左到右</td>
		</tr>
	</tbody>
</table>			<!-- 其他扩展 -->
						
			</div>
			
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		<li class="comment even thread-even depth-1" id="comment-11828"><span class="comt-f">#0</span><div class="comt-avatar wrapper"><i style="font-size:36px;" class="fa fa-user-circle" aria-hidden="true"></i><div class="tooltip"><p><i class="fa fa-user" aria-hidden="true"></i>&nbsp;&nbsp;&nbsp;stinkaroo</p><p><i class="fa fa-envelope" aria-hidden="true"></i>&nbsp;&nbsp;190***276@qq.com</p></div><div id="runoobvote-id-11828" data-commid = "11828" class="upvotejs"><a class="upvote"></a> <span class="count">74</span></div></div><div class="comt-main" id="div-comment-11828"><p>
在判断一个实例引用的类型时，使用的是实际类型，而不是声明的类型。在下面的代码中，
</p><pre>
Vehicle v2 = new Car();    // v2 是 Car 类型
</pre>
<p>
v2 是 Car 类型，而不是 Vehicle 类型。
</p><pre>
class Vehicle {}

public class Car extends Vehicle {
    public static void main(String args[]){
        Car c1 = new Car();

        Vehicle v2 = new Car();    // v2 是 Car 类型
        Vehicle v3 = new Vehicle();

        //Car 是 Vehicle类型, Vehicle 不是 Car 类型
        boolean result1 =  c1 instanceof Vehicle;    // true
        boolean result2 =  v2 instanceof Car;        // true
        boolean result3 =  v2 instanceof Vehicle;    // true
        boolean result4 =  v3 instanceof Car;          // false

        System.out.println(result1);
        System.out.println(result2);
        System.out.println(result3);
        System.out.println(result4);
   }
}
</pre><div class="comt-meta wrapper"><span class="comt-author"><a target="_blank" href="javascript:;">stinkaroo</a><div class="tooltip tooltip1"><p><i class="fa fa-user" aria-hidden="true"></i>&nbsp;&nbsp;&nbsp;stinkaroo</p><p><i class="fa fa-envelope" aria-hidden="true"></i>&nbsp;&nbsp;190***276@qq.com</p></div></span>6年前 (2017-05-09)</div></div></li><!-- #comment-## -->
<li class="comment odd alt thread-odd thread-alt depth-1" id="comment-20479"><span class="comt-f">#0</span><div class="comt-avatar wrapper"><i style="font-size:36px;" class="fa fa-user-circle" aria-hidden="true"></i><div class="tooltip"><p><i class="fa fa-user" aria-hidden="true"></i>&nbsp;&nbsp;&nbsp;妇芳单身骗</p><p><i class="fa fa-envelope" aria-hidden="true"></i>&nbsp;&nbsp;lhm***@126.com</p></div><div id="runoobvote-id-20479" data-commid = "20479" class="upvotejs"><a class="upvote"></a> <span class="count">60</span></div></div><div class="comt-main" id="div-comment-20479"><p>子类是父类的类型，但父类不是子类的类型。</p>

<p>子类的实例可以声明为父类型，但父类的实例不能声明为子类型。</p>

<pre>class Vehicle {}

public class Car extends Vehicle {
    public static void main(String args[]){
        Vehicle v1 = new Vehicle(); //父类型
        Vehicle v2 = new Car(); //子类的实例可以声明为父类型
        Car c1 = new Car();    // 子类型
        Car c2 = new Vehicle(); //这句会报错，父类型的实例不能声明为子类型

        //Car（子类）是Vehicle（父类）类型, Vehicle（父类）不是Car（子类）类型
        boolean result1 =  c1 instanceof Vehicle;    // true
        boolean result2 =  c1 instanceof Car;        // true
        boolean result3 =  v1 instanceof Vehicle;    // true
        boolean result4 =  v1 instanceof Car;          // false
        boolean result5 =  v2 instanceof Vehicle;    // true
        boolean result6 =  v2 instanceof Car;          // true

        System.out.println(result1);
        System.out.println(result2);
        System.out.println(result3);
        System.out.println(result4);
        System.out.println(result5);
        System.out.println(result6);
   }
}</pre>
<p>从执行结果来看，虽然 v2 被声明为了 Vehicle（父类），但它既是 instanceof Vehicle，又是 instanceof Car，所以 v2 其实是 Car（子类），否则 v2 instanceof Car 应该为 false。</p><div class="comt-meta wrapper"><span class="comt-author"><a target="_blank" href="javascript:;">妇芳单身骗</a><div class="tooltip tooltip1"><p><i class="fa fa-user" aria-hidden="true"></i>&nbsp;&nbsp;&nbsp;妇芳单身骗</p><p><i class="fa fa-envelope" aria-hidden="true"></i>&nbsp;&nbsp;lhm***@126.com</p></div></span>6年前 (2017-11-17)</div></div></li><!-- #comment-## -->
<li class="comment even thread-even depth-1" id="comment-39753"><span class="comt-f">#0</span><div class="comt-avatar wrapper"><i style="font-size:36px;" class="fa fa-user-circle" aria-hidden="true"></i><div class="tooltip"><p><i class="fa fa-user" aria-hidden="true"></i>&nbsp;&nbsp;&nbsp;无尘</p><p><i class="fa fa-envelope" aria-hidden="true"></i>&nbsp;&nbsp;227***8875@qq.com</p></div><div id="runoobvote-id-39753" data-commid = "39753" class="upvotejs"><a class="upvote"></a> <span class="count">30</span></div></div><div class="comt-main" id="div-comment-39753"><p>加法的结合顺序 <strong>左-&gt;右 </strong>所以左侧计算完毕后才会计算右侧 因此结果不同:</p>

<pre>public static void main(String[] args) {   
  int a=2;   
  System.out.println(--a/2+(++a*2));  
  System.out.println(++a*2+--a/2);
}</pre>
<p>结果：</p>

<pre>4
7</pre><div class="comt-meta wrapper"><span class="comt-author"><a target="_blank" href="javascript:;">无尘</a><div class="tooltip tooltip1"><p><i class="fa fa-user" aria-hidden="true"></i>&nbsp;&nbsp;&nbsp;无尘</p><p><i class="fa fa-envelope" aria-hidden="true"></i>&nbsp;&nbsp;227***8875@qq.com</p></div></span>4年前 (2019-02-14)</div></div></li><!-- #comment-## -->
<li class="comment odd alt thread-odd thread-alt depth-1" id="comment-43297"><span class="comt-f">#0</span><div class="comt-avatar wrapper"><i style="font-size:36px;" class="fa fa-user-circle" aria-hidden="true"></i><div class="tooltip"><p><i class="fa fa-user" aria-hidden="true"></i>&nbsp;&nbsp;&nbsp;踏平南天山</p><p><i class="fa fa-envelope" aria-hidden="true"></i>&nbsp;&nbsp;981***943@qq.com</p><p><i class="fa fa-external-link" aria-hidden="true"></i> <a rel="nofollow" target="_blank" href="https://zhidao.baidu.com/question/76818376.html">&nbsp;&nbsp;参考地址</a></p></div><div id="runoobvote-id-43297" data-commid = "43297" class="upvotejs"><a class="upvote"></a> <span class="count">30</span></div></div><div class="comt-main" id="div-comment-43297"><p><strong data-title>Java 中的运算符的左右结合性是什么意思</strong></p>

<p>所有的数学运算符都认为是从左到右运算的，Java 语言中大部分运算符也是从左到右结合的，只有单目运算符、赋值运算符和三目运算符例外，其中，单目运算符、赋值运算符和三目运算符是从右向左结合的，也就是从右向左运算。</p>

 <p>乘法和加法是两个可结合的运算，也就是说，这两个运算符左右两边的操作数可以互换位置而不会影响结果。</p>


<p>当有多中运算符参与运算的时候，先要考虑优先级，有相同优先级的就看结合性以决定运算顺序。</p>

<p>因为这样，所以，如果没有两个相同优先级的运算，就不存在考虑结合性的问题了。一个 <span class="marked">?:</span> 是体现不出来结合性的。 请看这个：</p>

<pre>a?b:c?d:e</pre>

<p>这个要怎么算？先看优先级，两个一样。再看结合性，右结合，所以先算：</p>

<pre>c?d:e</pre>

<p>再算:</p><pre> a?b:(c?d:e)</pre> 
<p>这就是所谓右结合。如果是左结合的话 就是先算:</p><pre>a?b:c</pre>

<p>再算:</p> <pre>(a?b:c)?d:e</pre>

<p>实际上，一般结合性的问题都可以用括号来解决。</p><div class="comt-meta wrapper"><span class="comt-author"><a target="_blank" href="../note/43297">踏平南天山</a><div class="tooltip tooltip1"><p><i class="fa fa-user" aria-hidden="true"></i>&nbsp;&nbsp;&nbsp;踏平南天山</p><p><i class="fa fa-envelope" aria-hidden="true"></i>&nbsp;&nbsp;981***943@qq.com</p><p><i class="fa fa-external-link" aria-hidden="true"></i> <a rel="nofollow" target="_blank" href="https://zhidao.baidu.com/question/76818376.html">&nbsp;&nbsp;参考地址</a></p></div></span>4年前 (2019-06-02)</div></div></li><!-- #comment-## -->
<li class="comment even thread-even depth-1" id="comment-46072"><span class="comt-f">#0</span><div class="comt-avatar wrapper"><i style="font-size:36px;" class="fa fa-user-circle" aria-hidden="true"></i><div class="tooltip"><p><i class="fa fa-user" aria-hidden="true"></i>&nbsp;&nbsp;&nbsp;_h0pe</p><p><i class="fa fa-envelope" aria-hidden="true"></i>&nbsp;&nbsp;286***6825@qq.com</p><p><i class="fa fa-external-link" aria-hidden="true"></i> <a rel="nofollow" target="_blank" href="https://blog.csdn.net/dirden_lcg/article/details/80140123">&nbsp;&nbsp;参考地址</a></p></div><div id="runoobvote-id-46072" data-commid = "46072" class="upvotejs"><a class="upvote"></a> <span class="count">70</span></div></div><div class="comt-main" id="div-comment-46072"><p><span class="marked">C + = A</span> 与 <span class="marked">C = C + A</span> 是有区别的一句话总结： <strong>+= 运算符既可以实现运算，又不会更改 s 的数据类型；而后者，C 和 A 必须是同一类型，否则无法直接运算</strong>。</p>


<pre>public class Student{
    public static void main(String[] args){
        short s = 10;

        //s = s + 3; 编译不通过
        s = (short)(s + 1); //不建议如此实现
        s += 1;    //既可以实现运算，又不会更改s的数据类型
        System.out.println("输出变量");
    }
}</pre>

 <p>另外， <span class="marked">-=</span> ， <span class="marked">*=</span> ， <span class="marked">/=</span> 也应同理。</p>
<div class="comt-meta wrapper"><span class="comt-author"><a target="_blank" href="javascript:;">_h0pe</a><div class="tooltip tooltip1"><p><i class="fa fa-user" aria-hidden="true"></i>&nbsp;&nbsp;&nbsp;_h0pe</p><p><i class="fa fa-envelope" aria-hidden="true"></i>&nbsp;&nbsp;286***6825@qq.com</p><p><i class="fa fa-external-link" aria-hidden="true"></i> <a rel="nofollow" target="_blank" href="https://blog.csdn.net/dirden_lcg/article/details/80140123">&nbsp;&nbsp;参考地址</a></p></div></span>4年前 (2019-08-23)</div></div></li><!-- #comment-## -->
<li class="comment odd alt thread-odd thread-alt depth-1" id="comment-46217"><span class="comt-f">#0</span><div class="comt-avatar wrapper"><i style="font-size:36px;" class="fa fa-user-circle" aria-hidden="true"></i><div class="tooltip"><p><i class="fa fa-user" aria-hidden="true"></i>&nbsp;&nbsp;&nbsp;_h0pe</p><p><i class="fa fa-envelope" aria-hidden="true"></i>&nbsp;&nbsp;286***6825@qq.com</p></div><div id="runoobvote-id-46217" data-commid = "46217" class="upvotejs"><a class="upvote"></a> <span class="count">23</span></div></div><div class="comt-main" id="div-comment-46217"><p>& 和 &&、| 和 || 的区别</p>

<p><strong>区别 1：</strong> & 和 | 可以进行位运算，后者不能。</p>

<p><strong>区别 2：</strong> && 和 || 进行运算时有短路性，前者无。</p><div class="comt-meta wrapper"><span class="comt-author"><a target="_blank" href="javascript:;">_h0pe</a><div class="tooltip tooltip1"><p><i class="fa fa-user" aria-hidden="true"></i>&nbsp;&nbsp;&nbsp;_h0pe</p><p><i class="fa fa-envelope" aria-hidden="true"></i>&nbsp;&nbsp;286***6825@qq.com</p></div></span>4年前 (2019-08-28)</div></div></li><!-- #comment-## -->
<li class="comment even thread-even depth-1" id="comment-49044"><span class="comt-f">#0</span><div class="comt-avatar wrapper"><i style="font-size:36px;" class="fa fa-user-circle" aria-hidden="true"></i><div class="tooltip"><p><i class="fa fa-user" aria-hidden="true"></i>&nbsp;&nbsp;&nbsp;cf</p><p><i class="fa fa-envelope" aria-hidden="true"></i>&nbsp;&nbsp;211***3262@qq.com</p></div><div id="runoobvote-id-49044" data-commid = "49044" class="upvotejs"><a class="upvote"></a> <span class="count">13</span></div></div><div class="comt-main" id="div-comment-49044"><p>整数运算：</p>
<ul><li>
1、如果两个操作数有一个为 long，则结果也为 long。
</li><li>
2、没有 long 时，结果为 int。即使操作数全为 short、byte，结果也是 int。
</li></ul>
<pre>public class Main {
    public static void main(String[] args) {
        byte a = 1;
        int b = 2;
        long b2 = 3;
        byte c = a + b;  // 报错
        int c2 = b2 + b;  // 报错
    }
}</pre><div class="comt-meta wrapper"><span class="comt-author"><a target="_blank" href="javascript:;">cf</a><div class="tooltip tooltip1"><p><i class="fa fa-user" aria-hidden="true"></i>&nbsp;&nbsp;&nbsp;cf</p><p><i class="fa fa-envelope" aria-hidden="true"></i>&nbsp;&nbsp;211***3262@qq.com</p></div></span>3年前 (2019-12-05)</div></div></li><!-- #comment-## -->
<li class="comment odd alt thread-odd thread-alt depth-1" id="comment-53817"><span class="comt-f">#0</span><div class="comt-avatar wrapper"><i style="font-size:36px;" class="fa fa-user-circle" aria-hidden="true"></i><div class="tooltip"><p><i class="fa fa-user" aria-hidden="true"></i>&nbsp;&nbsp;&nbsp;discovery</p><p><i class="fa fa-envelope" aria-hidden="true"></i>&nbsp;&nbsp;dis***ery131794@163.com</p></div><div id="runoobvote-id-53817" data-commid = "53817" class="upvotejs"><a class="upvote"></a> <span class="count">17</span></div></div><div class="comt-main" id="div-comment-53817"><p>Java 中关联性顺序不同指左右结合的顺序不同，对于三目运算符，关联性是从右向左的。例如：</p>

<pre>a ? b: c ? d : e</pre>

<p>根据关联性结果为 <span class="marked">a ? b : (c ? d : e)</span>, 即将右侧运算作为一个整体来进行运算，先进行 a 条件的判断。</p>

<pre>int b = 2;
int d = (b&lt;1) ? ++b : (b&gt;1) ? --b : 2;
System.out.println(d) ;//结果为1, b的值为1

int b = 2;
int d = (b&gt;1) ? ++b : (b&gt;1) ? --b : 2;
System.out.println(d) ;//结果为3, b的值为3</pre><div class="comt-meta wrapper"><span class="comt-author"><a target="_blank" href="javascript:;">discovery</a><div class="tooltip tooltip1"><p><i class="fa fa-user" aria-hidden="true"></i>&nbsp;&nbsp;&nbsp;discovery</p><p><i class="fa fa-envelope" aria-hidden="true"></i>&nbsp;&nbsp;dis***ery131794@163.com</p></div></span>3年前 (2020-05-21)</div></div></li><!-- #comment-## -->
<li class="comment even thread-even depth-1" id="comment-64394"><span class="comt-f">#0</span><div class="comt-avatar wrapper"><i style="font-size:36px;" class="fa fa-user-circle" aria-hidden="true"></i><div class="tooltip"><p><i class="fa fa-user" aria-hidden="true"></i>&nbsp;&nbsp;&nbsp;wen</p><p><i class="fa fa-envelope" aria-hidden="true"></i>&nbsp;&nbsp;l.z***16@qq.com</p></div><div id="runoobvote-id-64394" data-commid = "64394" class="upvotejs"><a class="upvote"></a> <span class="count">8</span></div></div><div class="comt-main" id="div-comment-64394"><p>以下对两个右移操作符&gt;&gt;和&gt;&gt;&gt;进行测试：</p><pre>
public class Opetator {
    public static void main(String[] args) {
        byte b = -1;
        short s = -1;
        int i = -1;
        long l = -1;
        System.out.println("byte b = " + b);
        System.out.println("(b &gt;&gt; 1) = " + (b &gt;&gt; 1));
        System.out.println("(b &gt;&gt;&gt; 1) = " + (b &gt;&gt;&gt; 1));
        System.out.println(String.format("hexof (b &gt;&gt; 1) = %x", (b &gt;&gt; 1)));
        System.out.println(String.format("hexof (b &gt;&gt;&gt; 1) = %x", (b &gt;&gt;&gt; 1)));
        System.out.println("short s = " + s);
        System.out.println("(s &gt;&gt; 1) = " + (s &gt;&gt; 1));
        System.out.println("(s &gt;&gt;&gt; 1) = " + (s &gt;&gt;&gt; 1));
        System.out.println(String.format("hexof (s &gt;&gt; 1) = %x", (s &gt;&gt; 1)));
        System.out.println(String.format("hexof (s &gt;&gt;&gt; 1) = %x", (s &gt;&gt;&gt; 1)));
        System.out.println("int i = " + i);
        System.out.println("(i &gt;&gt; 1) = " + (i &gt;&gt; 1));
        System.out.println("(i &gt;&gt;&gt; 1) = " + (i &gt;&gt;&gt; 1));
        System.out.println(String.format("hexof (i &gt;&gt; 1) = %x", (i &gt;&gt; 1)));
        System.out.println(String.format("hexof (i &gt;&gt;&gt; 1) = %x", (i &gt;&gt;&gt; 1)));
        System.out.println("long l = " + l);
        System.out.println("(l &gt;&gt; 1) = " + (l &gt;&gt; 1));
        System.out.println("(l &gt;&gt;&gt; 1) = " + (l &gt;&gt;&gt; 1));
        System.out.println(String.format("hexof (l &gt;&gt; 1) = %x", (l &gt;&gt; 1)));
        System.out.println(String.format("hexof (l &gt;&gt;&gt; 1) = %x", (l &gt;&gt;&gt; 1)));
    }
}
</pre><p>输出：</p><pre>
byte b = -1
(b &gt;&gt; 1) = -1
(b &gt;&gt;&gt; 1) = 2147483647
hexof (b &gt;&gt; 1) = ffffffff
hexof (b &gt;&gt;&gt; 1) = 7fffffff
short s = -1
(s &gt;&gt; 1) = -1
(s &gt;&gt;&gt; 1) = 2147483647
hexof (s &gt;&gt; 1) = ffffffff
hexof (s &gt;&gt;&gt; 1) = 7fffffff
int i = -1
(i &gt;&gt; 1) = -1
(i &gt;&gt;&gt; 1) = 2147483647
hexof (i &gt;&gt; 1) = ffffffff
hexof (i &gt;&gt;&gt; 1) = 7fffffff
long l = -1
(l &gt;&gt; 1) = -1
(l &gt;&gt;&gt; 1) = 9223372036854775807
hexof (l &gt;&gt; 1) = ffffffffffffffff
hexof (l &gt;&gt;&gt; 1) = 7fffffffffffffff
</pre><p>可得出以下结论：</p><p>1. byte、short、int&nbsp;类型的右移操作都是先将左操作数转换为int类型，然后执行右移操作，结果也是int类型。</p><p>2. long&nbsp;类型的右移操作并没有对左操作数进行类型转换，结果也是long类型。</p><p>3. &gt;&gt;操作对左边空位补符号位，&gt;&gt;&gt;对左边空位补0。</p><div class="comt-meta wrapper"><span class="comt-author"><a target="_blank" href="javascript:;">wen</a><div class="tooltip tooltip1"><p><i class="fa fa-user" aria-hidden="true"></i>&nbsp;&nbsp;&nbsp;wen</p><p><i class="fa fa-envelope" aria-hidden="true"></i>&nbsp;&nbsp;l.z***16@qq.com</p></div></span>2年前 (2021-06-13)</div></div></li><!-- #comment-## -->
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